In order to, upon spinning at the rotor spinning machine, start the spinning process or, after the interruption of the spinning process, for example, based on a thread breakage or a quality cut or after the shutting down of the rotor spinning machine, resume the spinning process, a yarn end must always be prepared for the spinning-in process. For this purpose, it is necessary to fray the yarn end, in order to align the individual fibers of the yarn end for the spinning-in process and to free it of short fibers. The yarn end prepared for spinning-in must then be returned to the spinning rotor with a length that is measured as precisely as possible, in order to reconnect with the fiber material that is stored there.
For preparing yarn ends for spinning, preparing the yarn end pneumatically (for example) is known in the state of the art. Thereby, the yarn end is suspended on an air flow, which acts in the tangential, axial and or radial direction of the yarn end.
From DE 196 53 389 A1, preparing the yarn end by means of a rotating roller occupied with needles or saw teeth is further known. By means of such roller, it is possible to open wrap fibers typically present in rotor yarn, which can hamper the pneumatic preparation of the yarn end. Following the opening of the wrap fibers, a pneumatic preparation of the yarn end is carried out in turn.
From DE 10 2012 110 926 A1, preparing the yarn end by means of the edge area of the rotating spinning rotor is further known. For this purpose, with an at least partially opened rotor housing, the yarn is brought into the vicinity of the open edge of the spinning rotor. The spinning rotor is set in rotation and the cover of the rotor housing is closed, such that the yarn end is then pressed against the open edge of the rotor and severed. For this purpose, the edge of the spinning rotor is provided with a roughening or an abrasive. According to an additional embodiment, the yarn is introduced into the closed rotor housing, whereas a single driven rotor is displaced in its axial direction. After the introduction of the yarn end, the rotor is once again moved into its operating position and is set in rotation, such that, through the ramp-up of the rotor, an interruption of the yarn end arises. By means of this type of preparation of the yarn end, disrupting wrap fibers are opened and the preparation of the yarn end can be performed directly at the spinning station. However, this can lead to differences in the quality of the preparation of the yarn end with regard to the length and fraying of the yarn end.